This project is designed to test the hypothesis that glycosaminoglycan (GAG) containing components of the extracellular matrix have a major influence on neural developmental events including cellular adhesion and neuronal axonation. A variety of studies have indicated that the GAG content of the extracellular matrix is high during the period of cell body migration and axon formation in both the central and peripheral nervous system. In vitro adhesion assays in our laboratory indicate cell lines of neural crest origin bind more readily to mixed collagen - GAG layers than to collagen alone. The adhesion of clonal and primary culture central nervous system neurons to artificial GAG-collagen layers will be examined in an in vitro adhesion assay to determine if thse cells show the same preference for GAG-collagen layers shown by peripheral nervous system cells. The ability of both central and peripheral nervous system neurons to extend axons on artificial matrices composed of individual GAG's and also on cell derived GAG layers will be examined. Using solid phase GAG's, cellular "receptors" for GAG's will be isolated from neural tissue by affinity chromatography, characterized, and antibodies to the receptors produced. Initial efforts will be to produce antibodies to the cell surface hyaluronic acid receptor of N18 mouse neuroblastoma cells. These antibodies will be used to determine which neural cell types express receptors for individual GAG's. They will also be used to examine receptor presence on growing axons and in two developing neural systems: migrating neural crest and closing neural tube. This combined biochemical, immunological, and cell biological approach will rigorously test the role of GAG's in neural adhesion and axonation and also indicate their potential role in other critical events in normal nervous system developoment.